Description

RPC routines allow C programs to make procedure calls on other machines
across the network. First, the client calls a procedure to send a
request to the server. Upon receipt of the request, the server calls
a dispatch routine to perform the requested service, and then sends back a
reply. Finally, the procedure call returns to the client.

The routines described in this manual page have been superseded by other
routines. The preferred routine is given after the description of the routine.
New programs should use the preferred routines, as support for the older
interfaces may be dropped in future releases.

File Descriptors

Some of the routines described in this section (such as clnttcp_create()) take
a pointer to a file descriptor as one of the parameters. If
the user wants the file descriptor to be a socket, then the
application will have to be linked with both librpcsoc and libnsl.
If the user passed RPC_ANYSOCK as the file descriptor, and the
application is linked with libnsl only, then the routine will return a
TLI file descriptor and not a socket.

Routines

The following routines require that the header <rpc/rpc.h> be included. The symbol
PORTMAP should be defined so that the appropriate function declarations for the
old interfaces are included through the header files.

authdes_create()

authdes_create() is the first of two routines which interface to the RPC secure authentication system, known as DES authentication. The second is authdes_getucred(), below. Note: the keyserver daemon keyserv(1M) must be running for the DES authentication system to work.

authdes_create(), used on the client side, returns an authentication handle that will enable the use of the secure authentication system. The first parameter name is the network name, or netname, of the owner of the server process. This field usually represents a hostname derived from the utility routine host2netname(), but could also represent a user name using user2netname(). See secure_rpc(3NSL). The second field is window on the validity of the client credential, given in seconds. A small window is more secure than a large one, but choosing too small of a window will increase the frequency of resynchronizations because of clock drift. The third parameter syncaddr is optional. If it is NULL, then the authentication system will assume that the local clock is always in sync with the server's clock, and will not attempt resynchronizations. If an address is supplied, however, then the system will use the address for consulting the remote time service whenever resynchronization is required. This parameter is usually the address of the RPC server itself. The final parameter ckey is also optional. If it is NULL, then the authentication system will generate a random DES key to be used for the encryption of credentials. If it is supplied, however, then it will be used instead.

This routine exists for backward compatibility only, and it is made obsolete by authdes_seccreate(). See secure_rpc(3NSL).

authunix_create()

Create and return an RPC authentication handle that contains .UX authentication information. The parameter host is the name of the machine on which the information was created; uid is the user's user ID; gid is the user's current group ID; grouplen and gidlistp refer to a counted array of groups to which the user belongs.

It is not very difficult to impersonate a user.

This routine exists for backward compatibility only, and it is made obsolete by authsys_create(). See rpc_clnt_auth(3NSL).

authunix_create_default()

Call authunix_create() with the appropriate parameters.

This routine exists for backward compatibility only, and it is made obsolete by authsys_create_default(). See rpc_clnt_auth(3NSL).

callrpc()

Call the remote procedure associated with prognum, versnum, and procnum on the machine, host. The parameter inproc is used to encode the procedure's parameters, and outproc is used to decode the procedure's results; in is the address of the procedure's argument, and out is the address of where to place the result(s). This routine returns 0 if it succeeds, or the value of enum clnt_stat cast to an integer if it fails. The routine clnt_perrno() is handy for translating failure statuses into messages. See rpc_clnt_calls(3NSL).

You do not have control of timeouts or authentication using this routine. This routine exists for backward compatibility only, and is made obsolete by rpc_call(). See rpc_clnt_calls(3NSL).

clnt_stat_clnt_broadcast()

Like callrpc(), except the call message is broadcast to all locally connected broadcast nets. Each time the caller receives a response, this routine calls eachresult(), whose form is:

eachresult(char *out, struct sockaddr_in *addr);

where out is the same as out passed to clnt_broadcast(), except that the remote procedure's output is decoded there; addr points to the address of the machine that sent the results. If eachresult() returns 0. clnt_broadcast() waits for more replies; otherwise it returns with appropriate status. If eachresult() is NULL, clnt_broadcast() returns without waiting for any replies.

Broadcast packets are limited in size to the maximum transfer unit of the transports involved. For Ethernet, the callers argument size is approximately 1500 bytes. Since the call message is sent to all connected networks, it may potentially lead to broadcast storms. clnt_broadcast() uses SB AUTH_SYS credentials by default. See rpc_clnt_auth(3NSL). This routine exists for backward compatibility only, and is made obsolete by rpc_broadcast(). See rpc_clnt_calls(3NSL).

clntraw_create()

This routine creates an internal, memory-based RPC client for the remote program prognum, version versnum. The transport used to pass messages to the service is actually a buffer within the process's address space, so the corresponding RPC server should live in the same address space. See svcraw_create(). This allows simulation of RPC and acquisition of RPC overheads, such as round trip times, without any kernel interference. This routine returns NULL if it fails.

This routine exists for backward compatibility only. It has the same functionality as clnt_raw_create(). See rpc_clnt_create(3NSL), which obsoletes it.

clnttcp_create()

This routine creates an RPC client for the remote program prognum, version versnum; the client uses TCP/IP as a transport. The remote program is located at Internet address addr. If addr->sin_port is 0, then it is set to the actual port that the remote program is listening on. The remote rpcbind service is consulted for this information. The parameter *fdp is a file descriptor, which may be open and bound; if it is RPC_ANYSOCK, then this routine opens a new one and sets *fdp. Refer to the File Descriptor section for more information. Since TCP-based RPC uses buffered I/O, the user may specify the size of the send and receive buffers with the parameters sendsz and recvsz. Values of 0 choose suitable defaults. This routine returns NULL if it fails.

This routine exists for backward compatibility only. clnt_create(), clnt_tli_create(), or clnt_vc_create() should be used instead. See rpc_clnt_create(3NSL).

clntudp_bufcreate()

Create a client handle for the remote program prognum, on versnum; the client uses UDP/IP as the transport. The remote program is located at the Internet address addr. If addr->sin_port is 0, it is set to port on which the remote program is listening on (the remote rpcbind service is consulted for this information). The parameter *fdp is a file descriptor, which may be open and bound. If it is RPC_ANYSOCK, then this routine opens a new one and sets *fdp. Refer to the File Descriptor section for more information. The UDP transport resends the call message in intervals of wait time until a response is received or until the call times out. The total time for the call to time out is specified by clnt_call(). See rpc_clnt_calls(3NSL). If successful it returns a client handle, otherwise it returns NULL. The error can be printed using the clnt_pcreateerror() routine. See rpc_clnt_create(3NSL).

The user can specify the maximum packet size for sending and receiving by using sendsz and recvsz arguments for UDP-based RPC messages.

If addr->sin_port is 0 and the requested version number versnum is not registered with the remote portmap service, it returns a handle if at least a version number for the given program number is registered. The version mismatch is discovered by a clnt_call() later (see rpc_clnt_calls(3NSL)).

This routine exists for backward compatibility only. clnt_tli_create() or clnt_dg_create() should be used instead. See rpc_clnt_create(3NSL).

clntudp_create()

This routine creates an RPC client handle for the remote program prognum, version versnum; the client uses UDP/IP as a transport. The remote program is located at Internet address addr. If addr->sin_port is 0, then it is set to actual port that the remote program is listening on. The remote rpcbind service is consulted for this information. The parameter *fdp is a file descriptor, which may be open and bound; if it is RPC_ANYSOCK, then this routine opens a new one and sets *fdp. Refer to the File Descriptor section for more information. The UDP transport resends the call message in intervals of wait time until a response is received or until the call times out. The total time for the call to time out is specified by clnt_call(). See rpc_clnt_calls(3NSL). clntudp_create() returns a client handle on success, otherwise it returns NULL. The error can be printed using the clnt_pcreateerror() routine. See rpc_clnt_create(3NSL).

Since UDP-based RPC messages can only hold up to 8 Kbytes of encoded data, this transport cannot be used for procedures that take large arguments or return huge results.

This routine exists for backward compatibility only. clnt_create(), clnt_tli_create(), or clnt_dg_create() should be used instead. See rpc_clnt_create(3NSL).

get_myaddress()

Places the local system's IP address into *addr, without consulting the library routines that deal with /etc/hosts. The port number is always set to htons(PMAPPORT).

This routine is only intended for use with the RPC library. It returns the local system's address in a form compatible with the RPC library, and should not be taken as the system's actual IP address. In fact, the *addr buffer's host address part is actually zeroed. This address may have only local significance and should not be assumed to be an address that can be used to connect to the local system by remote systems or processes.

This routine remains for backward compatibility only. The routine netdir_getbyname() should be used with the name HOST_SELF to retrieve the local system's network address as a netbuf structure. See netdir(3NSL).

getrpcport()

getrpcport() returns the port number for the version versnum of the RPC program prognum running on host and using protocol proto. getrpcport() returns 0 if the RPC system failed to contact the remote portmap service, the program associated with prognum is not registered, or there is no mapping between the program and a port.

This routine exists for backward compatibility only. Enhanced functionality is provided by rpcb_getaddr(). See rpcbind(3NSL).

pmaplist()

A user interface to the portmap service, which returns a list of the current RPC program-to-port mappings on the host located at IP address addr. This routine can return NULL . The command `rpcinfo-p' uses this routine.

This routine exists for backward compatibility only, enhanced functionality is provided by rpcb_getmaps(). See rpcbind(3NSL).

pmap_getport()

A user interface to the portmap service, which returns the port number on which waits a service that supports program prognum, version versnum, and speaks the transport protocol associated with protocol. The value of protocol is most likely IPPROTO_UDP or IPPROTO_TCP. A return value of 0 means that the mapping does not exist or that the RPC system failured to contact the remote portmap service. In the latter case, the global variable rpc_createerr contains the RPC status.

This routine exists for backward compatibility only, enhanced functionality is provided by rpcb_getaddr(). See rpcbind(3NSL).

pmap_rmtcall()

Request that the portmap on the host at IP address *addr make an RPC on the behalf of the caller to a procedure on that host. *portp is modified to the program's port number if the procedure succeeds. The definitions of other parameters are discussed in callrpc() and clnt_call(). See rpc_clnt_calls(3NSL).

This procedure is only available for the UDP transport.

If the requested remote procedure is not registered with the remote portmap then no error response is returned and the call times out. Also, no authentication is done.

This routine exists for backward compatibility only, enhanced functionality is provided by rpcb_rmtcall(). See rpcbind(3NSL).

pmap_set()

A user interface to the portmap service, that establishes a mapping between the triple [prognum, versnum, protocol] and port on the machine's portmap service. The value of protocol may be IPPROTO_UDP or IPPROTO_TCP. Formerly, the routine failed if the requested port was found to be in use. Now, the routine only fails if it finds that port is still bound. If port is not bound, the routine completes the requested registration. This routine returns 1 if it succeeds, 0 otherwise. Automatically done by svc_register().

This routine exists for backward compatibility only, enhanced functionality is provided by rpcb_set(). See rpcbind(3NSL).

pmap_unset()

A user interface to the portmap service, which destroys all mapping between the triple [prognum, versnum, all-protocols] and port on the machine's portmap service. This routine returns one if it succeeds, 0 otherwise.

This routine exists for backward compatibility only, enhanced functionality is provided by rpcb_unset(). See rpcbind(3NSL).

svc_fds()

A global variable reflecting the RPC service side's read file descriptor bit mask; it is suitable as a parameter to the select() call. This is only of interest if a service implementor does not call svc_run(), but rather does his own asynchronous event processing. This variable is read-only , yet it may change after calls to svc_getreq() or any creation routines. Do not pass its address to select()! Similar to svc_fdset, but limited to 32 descriptors.

This routine returns the network address, represented as a struct sockaddr_in, of the caller of a procedure associated with the RPC service transport handle, xprt.

This routine exists for backward compatibility only, and is obsolete. The preferred interface is svc_getrpccaller(). See rpc_svc_reg(3NSL), which returns the address as a struct netbuf.

svc_getreq()

This routine is only of interest if a service implementor does not call svc_run(), but instead implements custom asynchronous event processing. It is called when the select() call has determined that an RPC request has arrived on some RPC file descriptors; rdfds is the resultant read file descriptor bit mask. The routine returns when all file descriptors associated with the value of rdfds have been serviced. This routine is similar to svc_getreqset() but is limited to 32 descriptors.

This interface is made obsolete by svc_getreqset()

svcfd_create()

Create a service on top of any open and bound descriptor. Typically, this descriptor is a connected file descriptor for a stream protocol. Refer to the File Descriptor section for more information. sendsz and recvsz indicate sizes for the send and receive buffers. If they are 0, a reasonable default is chosen.

This routine creates an internal, memory-based RPC service transport, to which it returns a pointer. The transport is really a buffer within the process's address space, so the corresponding RPC client should live in the same address space; see clntraw_create(). This routine allows simulation of RPC and acquisition of RPC overheads (such as round trip times), without any kernel interference. This routine returns NULL if it fails.

This routine exists for backward compatibility only, and has the same functionality of svc_raw_create(). See rpc_svc_create(3NSL), which obsoletes it.

svctcp_create()

This routine creates a TCP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the file descriptor fd, which may be RPC_ANYSOCK, in which case a new file descriptor is created. If the file descriptor is not bound to a local TCP port, then this routine binds it to an arbitrary port. Refer to the File Descriptor section for more information. Upon completion, xprt->xp_fd is the transport's file descriptor, and xprt->xp_port is the transport's port number. This routine returns NULL if it fails. Since TCP-based RPC uses buffered I/O, users may specify the size of buffers; values of 0 choose suitable defaults.

This routine exists for backward compatibility only. svc_create(), svc_tli_create(), or svc_vc_create() should be used instead. See rpc_svc_create(3NSL).

svcudp_bufcreate()

This routine creates a UDP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the file descriptor fd. If fd is RPC_ANYSOCK then a new file descriptor is created. If the file descriptor is not bound to a local UDP port, then this routine binds it to an arbitrary port. Upon completion, xprtxp_fd is the transport's file descriptor, and xprt->xp_port is the transport's port number. Refer to the File Descriptor section for more information. This routine returns NULL if it fails.

The user specifies the maximum packet size for sending and receiving UDP-based RPC messages by using the sendsz and recvsz parameters.

This routine exists for backward compatibility only. svc_tli_create(), or svc_dg_create() should be used instead. See rpc_svc_create(3NSL).

svcudp_create()

This routine creates a UDP/IP-based RPC service transport, to which it returns a pointer. The transport is associated with the file descriptor fd, which may be RPC_ANYSOCK, in which case a new file descriptor is created. If the file descriptor is not bound to a local UDP port, then this routine binds it to an arbitrary port. Upon completion, xprt->xp_fd is the transport's file descriptor, and xprt->xp_port is the transport's port number. This routine returns NULL if it fails.

Since UDP-based RPC messages can only hold up to 8 Kbytes of encoded data, this transport cannot be used for procedures that take large arguments or return huge results.

This routine exists for backward compatibility only. svc_create(), svc_tli_create(), or svc_dg_create() should be used instead. See rpc_svc_create(3NSL).

registerrpc()

Register program prognum, procedure procname, and version versnum with the RPC service package. If a request arrives for program prognum, version versnum, and procedure procnum, procname is called with a pointer to its parameter(s). procname should return a pointer to its static result(s). inproc is used to decode the parameters while outproc is used to encode the results. This routine returns 0 if the registration succeeded, -1 otherwise.

svc_run() must be called after all the services are registered.

This routine exists for backward compatibility only, and it is made obsolete by rpc_reg().

svc_register()

Associates prognum and versnum with the service dispatch procedure, dispatch. If protocol is 0, the service is not registered with the portmap service. If protocol is non-zero, then a mapping of the triple [prognum, versnum, protocol] to xprt->xp_port is established with the local portmap service (generally protocol is 0, IPPROTO_UDP or IPPROTO_TCP). The procedure dispatch has the following form:

dispatch(struct svc_req *request, SVCXPRT *xprt);

The svc_register() routine returns one if it succeeds, and 0 otherwise.

This routine exists for backward compatibility only. Enhanced functionality is provided by svc_reg().

svc_unregister()

Remove all mapping of the double [prognum, versnum] to dispatch routines, and of the triple [prognum, versnum, all-protocols] to port number from portmap.

This routine exists for backward compatibility. Enhanced functionality is provided by svc_unreg().

xdr_authunix_parms()

Used for describing UNIX credentials. This routine is useful for users who wish to generate these credentials without using the RPC authentication package.

This routine exists for backward compatibility only, and is made obsolete by xdr_authsys_parms(). See rpc_xdr(3NSL).